An electric car or a hybrid car is provided with a high-voltage battery as a driving source for a drive motor, an AC/DC converter (charger), and a DC/DC converter. The AC/DC converter converts an AC voltage supplied from an external commercial AC power supply to a DC voltage and charges the high-voltage battery with the DC voltage. The DC/DC converter converts a high DC voltage from the AC/DC converter or the high-voltage battery to a low voltage and supplies the low voltage to an auxiliary machine. The auxiliary machine includes, for example, a car navigation system and lamplights which are driven with a low voltage.
For example, as described in JP 2014-3750 A, an AC/DC converter mainly includes a filter circuit, a power factor correction circuit, a full bridge circuit, a transformer, and a rectifier circuit. A DC/DC converter mainly includes a filter circuit, a full bridge circuit, a transformer, and a rectifier circuit. The AC/DC converter, the DC/DC converter, and a control unit that controls the AC/DC converter and the DC/DC converter together constitute a single power conversion apparatus.
On the other hand, for example, JP 2009-27901 A, JP 2013-211943 A, and JP 2013-99053 A each disclose a power conversion apparatus in which a power module (for example, an inverter) for driving a drive motor, a DC/DC converter, and a cooling body that cools the power module and the DC/DC converter are integrated. A flow path through which a coolant flows is formed inside the cooling body. The DC/DC converter is mounted on the upper face of the cooling body. The power module is mounted on the lower face of the cooling body.
An AC/DC converter, a DC/DC converter, and a power module differ in the number of electric circuits and electronic components and also in the area occupied by the electric circuits and the electronic components. Thus, when the DC/DC converter is mounted on either the upper face or the lower face of the cooling body and the power module is mounted on the other face as disclosed in JP 2009-27901 A, JP 2013-211943 A, and JP 2013-99053 A, it is necessary to design the size in the width direction of the cooling body and the apparatus in accordance with the face having a larger number of electric circuits and electronic components. This interferes with downsizing of the apparatus.